Sbc 355 Build-head Choice.
Im finishing up a 357 build. This is every other daily driver. I want good torque and HP. I have a set of World Product Sportsman II heads(200cccc) or a set of Patriot Vortec heads(185cc). Here is the rest of the combo. I know you guys will lead me in the best direction as you did with previous builds.
010 block 4 bolt main .40 bore
Balanced rotating assembly
Forged flat tops (9.72 compression)
LUNATI voodoo 268 227/233@50
Air Gap Intake
Holley 650 double Pumper
1.6 Comp roller rockers
Hooker Comp Shorty headers 1 5/8
Turbo 350 2200 stall
10 bolt 3.73
Like I said before, this is a car I will drive pretty often. I have my "hot rods", I just want a strong toy to drive around. Any help suggestions and advice is accepted. Thanks in advance guys.
If your asking which set of heads to use the answer is obvious. Use the smaller runner 185cc heads. They`ll fit in nicely with the combo you`ve got picked out. Save the 200cc heads for a 383 or a 400.
I was going to say the 200cc heads are the obvious choice with that combo. Look art what GM had learned about runner size...
Vortec port- this means you will need sa Vortec intake to match
Patriot on Left, Sportsman 2 on Right
The vortecs are the bettefr head, I didn consider the chamber. I don't know if patriots are still poorly machined but you may want to have them checked. The better chamber far outweighs the smaller runner.
My goof, good job cobalt.
Back off a little on the cam to build more cylinder pressure. Here are some suggestions....
And the winner at 110 LSA, reasonable ramps and $95 for cam and lifters is....
KB's calculator puts DCR at 8.6:1. With a tight squish, this DCR will work well on pump gas. Use all Lunati components listed in the lower right of the cam card.
I don't use or recommend flat tappet lifter cams any longer due to their "iffy" interaction at the lobe/lifter interface, but will make an exception in suggesting pieces for your build. You can help to protect yourself a little when using them by using this list of suggestions....
and by using a comparison between advertised and 0.050" tappet lift figures. I noticed for years that Crane always used a difference of 56 degrees between the two figures, in other words, if they ground a cam with advertised intake duration at....maybe 280 degrees, the 0.050" duration would be at least 56 degrees less, like maybe 224 degrees. This relationship, to me, indicates that the ramps will be reasonable in their lift rate because it was the standard difference in Crane's cam grinding for decades. As the difference between the two numbers gets smaller, it is an indication to me that the cam and all the rest of the valvetrain components are doing more work. I don't want them to do more work, so I opt for a large number between advertised and 0.050" figures on the intake lobes. Snappy valve action is great with roller lifters, but it ain't worth a hoot with flat tappets. Look at the last cam I listed above, the Lunati 00016LK. The intake duration at advertised (more than likely 0.005" tappet lift) is 284. The intake duration at 0.050" is 218. Subtract and find 66 degrees difference. This would indicate easy ramps instead of "snappy" valve action, an indication that the cam will live a long, happy life if all the other cautions are followed. The small amount of additional power that you might get with a snappy valve action cam such as an "Extreme Energy" grind will not be worth it when you frag the cam and have to start over. An example of an extreme cam that would be in the same category as the cams I listed above would be this CompCams offering....
Deducting 0.050" from advertised finds only 44 degrees difference. A grind such as this would work great with roller lifters, but I would not use it with flat tappet lifters.
You fellows will likely have to build a few motors and record how they react to different components before you are able to build one in your head that will be optimum.
Lose the short intake manifold. Use Edelbrock RPM 7101 or Weiand Stealth #8016 or Holley #300-36 or Professional Products Typhoon #52020/52021/52022.
Weiand does not make the #8016 Stealth anymore, but apparently Amazon has cornered a few units as old stock....
Lose the double pumper. Vacuum secondaries will work better on a street driver using a relatively short cam such as I have recommended above.
650 is all the CFM you will need. Use a double pumper with a minimum 3000 stall converter or stick shift car. Use Edelbrock 18059 reconditioned Thunder 650 with manual choke for this application.
Use Edelbrock #8013 choke cable.
Lose the 1.6 rockers, use standard 1.5 units made by an aftermarket producer to insure that the rockers will actually be 1.5:1. Stock Chevy rockers are nowhere close to 1.5:1, probably 1.3 to 1.4 if you tested tham scientifically. The additional 8-10 hp you will achieve with 1.6 rockers will come at the price of reduced life and more wear and tear on the valvetrain.
Lose the shorty headers. Install full-length, tuned 1 5/8" headers. Install H or X pipe right after the collectors. Shorties are better than cast iron logs, but inferior to long tube, tuned headers. Do it right the first time and you won't waste time and money doing it over again.
2200 stall converter and 3.73 gears will work fine.
Top the carb with enough filter area to allow the motor to breathe. I like to use a minimum 3" x 14" filter element. If you can't find a 3, then stack two 2" elements for a 4" x 14". If the motor cannot breathe easily, it cannot make the power that you are expecting from it.
Start with ignition timing at 12 degrees BTDC at the crank and 22 degrees at the weights. This will give a total of 34. If you find that you need a little more at the top, move the crank timing to 14 for a total of 36. Have all ignition lead in by 2800-3000 rpm's.
The Sportsmans are designed to hit certain track rules requiring the use of older GM style heads, as a result they haven't had the chamber improved since that of the old angle plug 292 head. They're fine for what they are intended for, but there's much better stuff out there for everyday use. SR Torquers are in the same boat, just in case you've got a pair of them laying about.
Ok guys, made some decisions.
I bought the voodoo 262
Hooker full length headers. 1 5/8
Rear gears will be swapped out to 3.42
And pump gas here is 93 premium which I run on a 10.7 compression 406 and runs fine and makes 527 flywheel HP.
Was hoping u guys had HP and torque estimates.
I've checked computer Sims and I know everything on those are boosted.
Im looking for real world HP/ tq numbers.
Thanks for the pointers guys.
I just picked up my 357 short block I had done from the machine shop on Monday. I am right there with similar pistons and CR. I have the 650dp on the other motor thats coming out with Sanderson block huggers, Edelbrock Performer intake. I will be installing a Comp Extreme Energy 4x4 cam, the 262 I think was what I picked out. This is going in a Jeep. As for the Heads, go with the Vortecs. I am looking for a pair for mine because they are great street torque heads. The smaller intake runners are what helps build that torque and since it will be a daily driver it doesn't sound like you will be revving it sky high.
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